SWITCHING POWER SUPPLY DEVICE, SWITCHING POWER SUPPLY CONTROL METHOD AND ELECTRONIC APPARATUS

• US 20140362614A1
• Filed: 06/03/2014
• Published: 12/11/2014
• Est. Priority Date: 06/10/2013
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Koga, Tomohiro
• Granted Patent: US 9,502,963 B2
• Time in Patent Office: Days
• US Class Current: 363/21.17
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: H02M 3/1552 Boost converters exploiting the leakage inductance of a transformer or of an alternator as boost inductor
• CPC Class Codes: H02M 7/1557 with automatic control of the output voltage or current
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Provided is a switching power supply device in a critical mode, including a load detection section that detects a load. When the detected load is lighter than a setting value, an upper limit of a switching frequency is lowered stepwise.

Claims

1. A switching power supply device in a critical mode, comprising:

a load detection section that detects a load,

wherein when the detected load is lighter than a setting value, an upper limit of a switching frequency is lowered stepwise.

2. The switching power supply device according to claim 1, further comprising:

a series circuit of a coil and a semiconductor switching element;

a rectifier circuit, connected to the semiconductor switching element, in which an output is extracted; and

a pulse generator that generates a pulse signal for switching the semiconductor switching element,

wherein when a load is lighter than a setting value, the pulse generator is controlled in a direction in which an upper limit of a frequency of the pulse signal is lowered stepwise.

3. The switching power supply device according to claim 1, wherein the upper limit of the switching frequency is switched in three stages or more.

4. The switching power supply device according to claim 1, wherein a setting of a load for switching the switching frequency is changed depending on a rating of a power supply.

5. The switching power supply device according to claim 2, wherein a timing is detected by detecting zero of a current flowing to the coil.

6. The switching power supply device according to claim 2, wherein a case in which the load is light is detected from a feedback voltage of an output voltage or a voltage associated with the feedback voltage.

7. The switching power supply device according to claim 6, further comprising:

a state transition detection section that detects one state in a plurality of states including a normal operation state by comparing the feedback voltage of the output voltage or the voltage associated with the feedback voltage with a threshold;

a control section that sets the upper limit of the switching frequency and the threshold in accordance with the one state which is detected; and

a variable frequency signal oscillator that supplies a signal of the upper limit which is set by the control section to the pulse generator.

8. The switching power supply device according to claim 7, wherein a difference between a threshold for lowering the upper limit when the load becomes light and a threshold for raising the upper limit when the load becomes heavy is set.

9. The switching power supply device according to claim 7, wherein a reset function of transitioning directly from each of the plurality of states to the normal state is included.

10. The switching power supply device according to claim 7, wherein the state transition detection section includes:

a plurality of comparators that compare the feedback voltage or the voltage associated with the feedback voltage with a plurality of thresholds; and

a selector that selects one output in the plurality of comparators.

11. A method of controlling a switching power supply in a critical mode, comprising:

lowering an upper limit of a switching frequency stepwise when a load is detected and the detected load is lighter than a setting value.

12. An electronic apparatus comprising a switching power supply device in a critical mode,

wherein the switching power supply device includes a load detection section that detects a load, and

when the detected load is lighter than a setting value, an upper limit of a switching frequency is lowered stepwise.